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100+ Free ABC Wastewater Collection Class II Practice Questions

Pass your ABC Wastewater Collection Operator Class II Certification Exam exam on the first try — instant access, no signup required.

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ArticleFREE ABC Water Distribution Operator Exam Guide 2026: Class 1-4, 100 Questions, 70% Pass (Practice Questions)28 min read
2026 Statistics

Key Facts: ABC Wastewater Collection Class II Exam

100

Scored Questions

WPI Class II exam outline

+10

Possible Unscored Pretest

WPI need-to-know criteria

3 hours

Time Limit

WPI-style exam policy

70%

Passing Score

WPI-style exam policy

Class II

Small-to-Medium System Tier

ABC/WPI certification structure

$69+

WPI Exam Sitting Fee

WPI / PSI exam process

The ABC/WPI Wastewater Collection Operator Class II exam uses the 2025 standardized blueprint with 100 scored multiple-choice questions, up to 10 unscored pretest items, a 3-hour time limit, and a 70% passing score. Class II covers all Class I fundamentals plus deeper lift station operations (pump types, affinity laws, alternation, VFDs, firm capacity), force main pigging and rehabilitation, NASSCO PACP/MACP/LACP coding, trenchless rehabilitation selection (CIPP, sliplining, pipe bursting), CMOM compliance (capacity, management, operation, maintenance), SSES and hydraulic modeling, FOG enforcement at scale, confined space and LOTO safety, and OT cybersecurity. Class II typically authorizes operation of small-to-medium collection systems, with thresholds set by each state.

Sample ABC Wastewater Collection Class II Practice Questions

Try these sample questions to test your ABC Wastewater Collection Class II exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A Class II operator must select a lift station pump for a wet well that receives gritty, stringy raw sewage with a peak design flow of 350 gpm at 35 ft TDH. Which pump type is the best primary choice?
A.Submersible non-clog centrifugal pump
B.Air-operated diaphragm pump
C.Progressive cavity pump
D.Peristaltic hose pump
Explanation: Submersible non-clog centrifugal pumps are the workhorse of municipal lift stations because their wide passageways (often 3 inches or larger) handle stringy material, rags, and grit at typical lift-station flows and heads. Diaphragm and peristaltic pumps are used for sampling or chemical feed, not raw sewage at this scale. Progressive cavity pumps handle solids well but clog on rags and are usually reserved for thick sludge.
2According to the affinity laws, if a variable-frequency drive reduces a lift station pump from 60 Hz to 45 Hz, the pump's flow will change by approximately what factor?
A.Multiplied by 0.56
B.Multiplied by 0.75
C.Multiplied by 0.42
D.Multiplied by 0.88
Explanation: The affinity laws state that flow varies directly with pump speed: Q2 = Q1 times (N2 divided by N1). So 45 Hz divided by 60 Hz equals 0.75, meaning flow drops to 75% of the original. Head varies with the square of speed (0.56) and brake horsepower with the cube (0.42), but the question specifically asks about flow.
3The operating point of a centrifugal lift station pump is best defined as:
A.The pump's best efficiency point shown on the manufacturer's curve
B.The intersection of the pump curve and the system head curve
C.The point where suction lift equals discharge head
D.The flow rate the operator dials in on the SCADA setpoint
Explanation: The operating point is the intersection of the pump curve (head a pump can produce at each flow) and the system head curve (head the piping system requires at each flow). Operating away from the best efficiency point wastes energy and causes wear. Operators should verify the operating point during commissioning and after major changes such as force main rehabilitation.
4A duplex submersible lift station uses lead/lag control. What is the main reason operators alternate the lead pump on each cycle?
A.It increases the firm capacity of the station
B.It distributes wear evenly between the two pumps
C.It is required by the NPDES permit for SSO reporting
D.It reduces the wet well minimum cycle time
Explanation: Alternating the lead pump on each pumpdown cycle equalizes runtime hours, bearing wear, seal wear, and impeller wear between the duplex pumps. Firm capacity (the capacity with the largest pump out of service) is set by the pump sizing, not by alternation. Alternation does not change permit requirements or wet well cycle times.
5A Ten States Standards-compliant lift station limits pump starts to approximately how many per hour for constant-speed motors above 7.5 hp?
A.2 starts per hour
B.6 starts per hour
C.10 starts per hour
D.24 starts per hour
Explanation: Ten States Standards and most pump manufacturers cap starts on across-the-line motors above 7.5 hp at about 6 per hour to prevent motor overheating from inrush current. Wet wells are sized so the difference between pump-on and pump-off elevations gives at least 10 minutes between starts at average flow. VFDs and soft starters allow more frequent starts because inrush current is limited.
6Lift station runtime data shows pump A is running 30% longer than pump B at the same wet well levels. What is the most likely cause?
A.Pump A has a worn impeller and is moving less flow per minute
B.Pump B has higher motor amps
C.The wet well is undersized
D.Pump B has a leaking discharge check valve
Explanation: If both pumps draw the same wet well down between the same on/off elevations but one runs noticeably longer, that pump is moving less water per minute. Worn impellers, partial clogging, or a worn wear ring all reduce capacity and increase runtime. Capacity testing (drawdown test or flow meter) confirms the problem. A leaking check valve usually causes backflow and recurring starts, not long runtime.
7Why are air release valves installed at the high points of a sewage force main?
A.To vent accumulated air or gas that would otherwise reduce effective flow area and cause surges
B.To inject air to keep wastewater aerobic and reduce H2S
C.To allow operator sampling of the force main contents
D.To reduce the static head on the lift station pumps
Explanation: Gas (mostly air, sometimes H2S and methane) collects at high points in a force main. Trapped gas reduces the cross-sectional flow area, raises friction loss, and increases the risk of damaging surges (water hammer). Combination air release/vacuum valves vent the gas and admit air to prevent collapse during pump shutdown. Force main air vents do not aerate the sewage and are not for sampling.
8An operator suspects grease and grit have built up in a 6-inch force main. Which rehabilitation method is most appropriate to recover capacity without excavation?
A.Pigging the force main with a soft polyurethane pig
B.Hydraulic pipe bursting with HDPE replacement
C.Cured-in-place pipe (CIPP) lining
D.Installing additional air release valves
Explanation: Pigging uses a foam, urethane, or polyurethane pig launched from a launching station and recovered downstream to scrape accumulated grease, grit, and biofilm off the force main wall, restoring effective diameter. Pipe bursting and CIPP are structural rehabilitation methods, not cleaning. Air release valves vent trapped gas but do not remove deposits.
9What is water hammer in a force main?
A.The pressure surge caused by sudden changes in fluid velocity, such as a pump trip or valve slam
B.Cavitation inside the lift station pump volute
C.The sound of grit striking the inside of the discharge piping
D.The vibration from out-of-balance impellers
Explanation: Water hammer is a transient pressure surge caused by a sudden change in fluid velocity. Common triggers in collection systems are pump trip on power loss and abrupt check valve closure. Surges can rupture force mains, damage pumps, and crack thrust blocks. Surge analysis and devices such as slow-closing check valves, air chambers, and surge tanks protect the system.
10Which trenchless rehabilitation method involves inverting or pulling a resin-saturated felt liner into the host pipe and curing it in place with steam, hot water, or ultraviolet light?
A.Sliplining
B.Cured-in-place pipe (CIPP)
C.Pipe bursting
D.Open-cut replacement
Explanation: Cured-in-place pipe (CIPP) uses a resin-saturated felt or fiberglass liner installed by inversion or winch pull, then cured by steam, hot water, or UV light. Once cured, it bonds tightly to the host pipe and seals cracks, infiltration points, and minor structural defects. Sliplining inserts a smaller pre-made pipe; pipe bursting fragments the old pipe while pulling new pipe through; open-cut requires excavation.

About the ABC Wastewater Collection Class II Exam

Class II practice exam for the ABC/WPI standardized wastewater collection operator certification used by most state programs. Class II authorizes operation of small-to-medium collection systems and adds advanced lift station operations, force main rehabilitation, CCTV program management, and CMOM compliance to the Class I foundation.

Assessment

100 scored multiple-choice questions plus up to 10 unscored pretest questions

Time Limit

180 minutes

Passing Score

70%

Exam Fee

Approximately $69 WPI exam sitting fee plus state application fees (Association of Boards of Certification (ABC) / Water Professionals International (WPI))

ABC Wastewater Collection Class II Exam Content Outline

35%

Operation, Maintenance, and Cleaning

Lift station pump selection, alternation, VFD operation and affinity laws, wet well sizing and firm capacity, force main scouring velocity, pigging, air release valves, water hammer, jet-vactor operation, nozzle selection, FOG inspection and enforcement, hot-spot management, and bypass pumping.

30%

Inspection, Assessment, and Rehabilitation

NASSCO PACP gravity main coding, MACP manhole coding, LACP lateral coding, CCTV defect interpretation, pre-CCTV cleaning, CIPP per ASTM F1216, sliplining, static pipe bursting, manhole rehabilitation with chimney seals and cementitious or epoxy lining, and rehabilitation method selection.

20%

Compliance, CMOM, and Asset Management

EPA CMOM elements (goals, organization, legal authority, O&M, design and performance, OERP), SSO reporting and root-cause analysis, consent decrees, SSES flow monitoring and hydrograph separation, hydraulic modeling, GIS asset management, risk-based renewal, AWIA Section 2013, NPDES, MS4 versus sanitary, and acceptance testing of new construction.

15%

Safety, Security, and Math

Permit-required confined space entry, atmospheric testing sequence, attendant duties, retrieval and rescue, LOTO of all energy sources, H2S corrosion mechanism and control, NIST CSF cybersecurity for OT/SCADA, wet well and force main volume math, peaking factors, R-factor, and electrical power calculations.

How to Pass the ABC Wastewater Collection Class II Exam

What You Need to Know

  • Passing score: 70%
  • Assessment: 100 scored multiple-choice questions plus up to 10 unscored pretest questions
  • Time limit: 180 minutes
  • Exam fee: Approximately $69 WPI exam sitting fee plus state application fees

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

ABC Wastewater Collection Class II Study Tips from Top Performers

1Master pump affinity laws cold: flow varies with speed, head varies with the square of speed, brake horsepower varies with the cube of speed.
2Memorize NASSCO PACP structural grades: 1 = minor, 5 = immediate failure risk, and understand the typical action horizons for grades 3, 4, and 5.
3Know the difference between CIPP, sliplining, and pipe bursting cold, including which method allows upsizing (pipe bursting) and which preserves nearly full diameter (CIPP).
4Learn the six CMOM elements: Goals, Organization, Legal Authority, Operation and Maintenance, Design and Performance, and Overflow Emergency Response Plan.
5Remember the OSHA confined space testing sequence: oxygen first, then LEL (combustibles), then toxics (H2S, CO), with safe oxygen of 19.5% to 23.5%.
6Practice wet well and force main volume math: V = 0.785 x D-squared x length (cubic feet) and 7.48 gallons per cubic foot. Class II routinely tests these.

Frequently Asked Questions

What is the ABC Wastewater Collection Operator Class II exam?

Class II is the second tier of the ABC/WPI standardized wastewater collection operator certification used by most state authorities. It authorizes operation of small-to-medium collection systems and adds advanced lift station operations, force main rehabilitation, CCTV program management, and CMOM compliance to the Class I foundation.

How many questions are on the Class II Collection exam?

The Class II Collection exam includes 100 scored multiple-choice questions and may include up to 10 unscored pretest items. Jurisdictions using the WPI format allow 3 hours and require a 70% passing score on the 100 scored questions.

How does Class II Collection differ from Class I?

Class II covers every Class I topic plus deeper lift station operations (pump selection, affinity laws, VFDs, alternation, firm capacity), force main rehabilitation (CIPP, sliplining, pipe bursting selection), NASSCO PACP/MACP/LACP coding, CMOM elements and OERP, SSES and hydraulic modeling, and OT cybersecurity. Class I focuses more on fundamentals and recall.

Is Class I required before Class II?

Most states require operators to hold Class I collection certification, plus documented operating experience, before sitting for Class II. Some jurisdictions allow direct entry to Class II for operators with significant prior experience. Confirm the rule with your state certifying authority.

What size system can a Class II collection operator run?

Class II typically authorizes operation of small-to-medium wastewater collection systems. Exact classification thresholds (population served, pipe miles, lift station count, complexity) are set by each state authority and are not uniform across jurisdictions.

How should I study for Class II Collection?

Focus first on lift station operations including pump types, affinity laws, alternation, and firm capacity. Then study NASSCO PACP/MACP/LACP coding and trenchless rehabilitation methods (CIPP, sliplining, pipe bursting). Finish with CMOM, SSES, safety, and math (volume, peaking factors, electrical power). Plan on 60-100 hours of study and complete timed practice sets above 70%.